Neovascularization of the cornea is a significant cause of decreased visual acuity and blindness. It occurs in patients with trachoma and herpetic keratitis as well as in traumatic, inflammatory, toxic and nutritional disorders. The progression of corneal neovascularization in experimental animals involves many distinct phases which can be broadly divided into: 1) a prevascular latent period; 2) a stage of neovascularization; and 3) a stage of vascular regression. Potential angiogenic factors responsible for neovascularization include mediators and components of the inflammatory response such as leukocytes, platelets, fibrin, eicosanoids and plasminogen activator. Corneal vascularization is markedly suppressed by total body irradiation. This is presumed to be largely secondary to radiation induced leukopenia which impairs the leukocytic infiltration into the cornea and to a lesser extent due to the effect of irradiation of the pericorneal vascularization. To further investigate the association of corneal neovascularization and leukocytes, we will study the effect of syngeneic bone marrow transplantation on the reversibility of the suppression of corneal angiogenesis in inbred irradiated rats. Fischer 344 inbred rats will receive either total body irradiation, irradiation of the head alone, or irradiation of the body alone. Control rats will receive no irradiation. Some rats receiving total body irradiation will undergo syngeneic bone marrow transplantation immediately following irradiation. Six days after irradiation when the peripheral leukocytic counts reach their lowest level following total body irradiation, corneas will be cauterized with silver/potassium nitrate under standard conditions that are known to reproducibly induce corneal neovascularization in the rat. Four days after injury, rats will be sacrificed and the vasculature will be immediately perfused with gelatin containing colloidal carbon. Corneal flat preparations will be analyzed in a masked fashion to quantitate corneal vascularization objectively by measurement of the resultant carbon filled corneal blood vessels by a computerized image analysis. The effects of irradiation and bone marrow reconstitution will be assessed by sequential complete blood counts, flow cytometry analysis of lymphocyte and mononuclear subsets in the peripheral blood and bone marrow and histologic examination of eyes and bone marrows.